KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

Manually perform cache maintenance on the source VM during intra-host
migration to ensure no stale data is left in CPU caches after the VM is
destroyed.  Because the source VM is "converted" to a non-SEV VM, KVM's
memory reclaim flows won't trigger cache maintenance, e.g. when all guest
memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option
as KVM doesn't require identical guest memory configurations, i.e. the
source VM may have access to memory that the destination VM does not.
Enforcing equivalent memory configurations is infeasible, as it would
require a *deep* comparison of memslots, e.g. to verify that not only are
the memslot identical, but what the memslots point at is also identical.

Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration")
Cc: stable@vger.kernel.org
Reported-by: Stefan Teodorescu <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 200 insertions, 0 deletions

diff --git a/drivers/soc/fsl/rcpm.c b/drivers/soc/fsl/rcpm.c
new file mode 100644
index 000000000..06bd94b29
--- /dev/null
+++ b/drivers/soc/fsl/rcpm.c
@@ -0,0 +1,200 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// rcpm.c - Freescale QorIQ RCPM driver
+//
+// Copyright 2019-2020 NXP
+//
+// Author: Ran Wang <ran.wang_1@nxp.com>
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/suspend.h>
+#include <linux/kernel.h>
+#include <linux/acpi.h>
+
+#define RCPM_WAKEUP_CELL_MAX_SIZE	7
+
+struct rcpm {
+	unsigned int	wakeup_cells;
+	void __iomem	*ippdexpcr_base;
+	bool		little_endian;
+};
+
+#define  SCFG_SPARECR8	0x051c
+
+static void copy_ippdexpcr1_setting(u32 val)
+{
+	struct device_node *np;
+	void __iomem *regs;
+	u32 reg_val;
+
+	np = of_find_compatible_node(NULL, NULL, "fsl,ls1021a-scfg");
+	if (!np)
+		return;
+
+	regs = of_iomap(np, 0);
+	of_node_put(np);
+	if (!regs)
+		return;
+
+	reg_val = ioread32be(regs + SCFG_SPARECR8);
+	iowrite32be(val | reg_val, regs + SCFG_SPARECR8);
+
+	iounmap(regs);
+}
+
+/**
+ * rcpm_pm_prepare - performs device-level tasks associated with power
+ * management, such as programming related to the wakeup source control.
+ * @dev: Device to handle.
+ *
+ */
+static int rcpm_pm_prepare(struct device *dev)
+{
+	int i, ret, idx;
+	void __iomem *base;
+	struct wakeup_source	*ws;
+	struct rcpm		*rcpm;
+	struct device_node	*np = dev->of_node;
+	u32 value[RCPM_WAKEUP_CELL_MAX_SIZE + 1];
+	u32 setting[RCPM_WAKEUP_CELL_MAX_SIZE] = {0};
+
+	rcpm = dev_get_drvdata(dev);
+	if (!rcpm)
+		return -EINVAL;
+
+	base = rcpm->ippdexpcr_base;
+	idx = wakeup_sources_read_lock();
+
+	/* Begin with first registered wakeup source */
+	for_each_wakeup_source(ws) {
+
+		/* skip object which is not attached to device */
+		if (!ws->dev || !ws->dev->parent)
+			continue;
+
+		ret = device_property_read_u32_array(ws->dev->parent,
+				"fsl,rcpm-wakeup", value,
+				rcpm->wakeup_cells + 1);
+
+		if (ret)
+			continue;
+
+		/*
+		 * For DT mode, would handle devices with "fsl,rcpm-wakeup"
+		 * pointing to the current RCPM node.
+		 *
+		 * For ACPI mode, currently we assume there is only one
+		 * RCPM controller existing.
+		 */
+		if (is_of_node(dev->fwnode))
+			if (np->phandle != value[0])
+				continue;
+
+		/* Property "#fsl,rcpm-wakeup-cells" of rcpm node defines the
+		 * number of IPPDEXPCR register cells, and "fsl,rcpm-wakeup"
+		 * of wakeup source IP contains an integer array: <phandle to
+		 * RCPM node, IPPDEXPCR0 setting, IPPDEXPCR1 setting,
+		 * IPPDEXPCR2 setting, etc>.
+		 *
+		 * So we will go thought them to collect setting data.
+		 */
+		for (i = 0; i < rcpm->wakeup_cells; i++)
+			setting[i] |= value[i + 1];
+	}
+
+	wakeup_sources_read_unlock(idx);
+
+	/* Program all IPPDEXPCRn once */
+	for (i = 0; i < rcpm->wakeup_cells; i++) {
+		u32 tmp = setting[i];
+		void __iomem *address = base + i * 4;
+
+		if (!tmp)
+			continue;
+
+		/* We can only OR related bits */
+		if (rcpm->little_endian) {
+			tmp |= ioread32(address);
+			iowrite32(tmp, address);
+		} else {
+			tmp |= ioread32be(address);
+			iowrite32be(tmp, address);
+		}
+		/*
+		 * Workaround of errata A-008646 on SoC LS1021A:
+		 * There is a bug of register ippdexpcr1.
+		 * Reading configuration register RCPM_IPPDEXPCR1
+		 * always return zero. So save ippdexpcr1's value
+		 * to register SCFG_SPARECR8.And the value of
+		 * ippdexpcr1 will be read from SCFG_SPARECR8.
+		 */
+		if (dev_of_node(dev) && (i == 1))
+			if (of_device_is_compatible(np, "fsl,ls1021a-rcpm"))
+				copy_ippdexpcr1_setting(tmp);
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops rcpm_pm_ops = {
+	.prepare =  rcpm_pm_prepare,
+};
+
+static int rcpm_probe(struct platform_device *pdev)
+{
+	struct device	*dev = &pdev->dev;
+	struct rcpm	*rcpm;
+	int ret;
+
+	rcpm = devm_kzalloc(dev, sizeof(*rcpm), GFP_KERNEL);
+	if (!rcpm)
+		return -ENOMEM;
+
+	rcpm->ippdexpcr_base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(rcpm->ippdexpcr_base)) {
+		ret =  PTR_ERR(rcpm->ippdexpcr_base);
+		return ret;
+	}
+
+	rcpm->little_endian = device_property_read_bool(
+			&pdev->dev, "little-endian");
+
+	ret = device_property_read_u32(&pdev->dev,
+			"#fsl,rcpm-wakeup-cells", &rcpm->wakeup_cells);
+	if (ret)
+		return ret;
+
+	dev_set_drvdata(&pdev->dev, rcpm);
+
+	return 0;
+}
+
+static const struct of_device_id rcpm_of_match[] = {
+	{ .compatible = "fsl,qoriq-rcpm-2.1+", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rcpm_of_match);
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id rcpm_acpi_ids[] = {
+	{"NXP0015",},
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, rcpm_acpi_ids);
+#endif
+
+static struct platform_driver rcpm_driver = {
+	.driver = {
+		.name = "rcpm",
+		.of_match_table = rcpm_of_match,
+		.acpi_match_table = ACPI_PTR(rcpm_acpi_ids),
+		.pm	= &rcpm_pm_ops,
+	},
+	.probe = rcpm_probe,
+};
+
+module_platform_driver(rcpm_driver);